1. Field of the Invention
The present invention relates to a medical manipulator for use in laparoscopic surgery, for example.
2. Description of the Related Art
According to a laparoscopic surgical operation process, a certain number of small holes are opened in the abdominal region, for example, of a patient, and a flexible scope and manipulators or forceps are inserted into the holes. The surgeon performs a surgical operation on the patient with the manipulators or forceps while watching an image captured by the flexible scope and displayed on a display monitor. Since the laparoscopic surgical operation process does not require a laparotomy, the surgical operation is less burdensome on the patient and greatly reduces the number of days required for the patient to spend before recovering from the operation and being released from the hospital. Therefore, the laparoscopic surgical operation process is expected to find and increased range of surgical operations to which it is applicable.
Manipulators for laparoscopic surgical operations are required to allow the operator, i.e., a surgeon, to perform various appropriate techniques quickly depending on the position and size of the affected part, for removing, suturing, and ligating (tying-knot) the affected part. Japanese Laid-Open Patent Publication No. 2002-102248, Japanese Laid-Open Patent Publication No. 2004-301275, and U.S. Pat. No. 6,889,116, for example, disclose manipulators that can be operated simply with a high degree of freedom.
Such manipulators employ a wire and pulley mechanism as a power transmitting mechanism, since a wire and pulley mechanism is simple in structure and exhibits high power transmitting efficiency.
When a surgeon uses forceps of a general nature in a laparoscopic surgery or in surgery using a flexible scope, external forces applied to the distal-end working unit of the forceps and gripping forces applied by the distal-end working unit are transmitted, not directly but as reactive forces, to the hand of the surgeon. Therefore, the surgeon is capable of feeling the forces to a certain extent and can operate the forceps based on such reactive forces. Forceps that have been available heretofore have only a few degrees of freedom, e.g., one degree of freedom, and are difficult to handle because they are movable only in limited directions for gripping and cutting tissues or for inserting suture needles, and require surgeon to be highly skilled when using them.
To achieve higher degrees of freedom, one option would be to use a master-slave remote control surgical robot, for example. Such a master-slave remote control surgical robot is advantageous in that it enables a high degree of freedom, can approach the affected part of a patient from various desired directions, and can be operated effectively and efficiently. However, external forces applied to the distal-end working unit, as well as gripping forces applied by the distal-end working unit, are not transmitted to the master side of the master-slave remote control surgical robot.
If a sensation of force is to be available on the master side of the master-slave remote control surgical robot, then the surgical robot system must be expensive and complex, as the system requires a highly sophisticated bilateral control architecture based on a highly sensitive force sensing system and a computer system having high-speed sampling times. In addition, in practice, bilateral control architecture has not yet reached a sufficient performance level at present.
The applicants have already proposed multiple-degree-of-freedom forceps, including a distal-end working unit having joints that can be actuated by motors based on commands from an operating unit. Since the operating unit, i.e., an operating handle, and the distal-end working unit, i.e., distal-end joints, are integrally coupled to each other, external forces applied to the distal-end working unit and gripping forces applied by the distal-end working unit are transmitted, not directly but via the multiple-degree-of-freedom forceps, to the operating unit. Therefore, an operator of the multiple-degree-of-freedom forceps can feel such forces to a certain extent. Nevertheless, there is a demand for a multiple-degree-of-freedom forceps, which can allow the operator to feel stronger external forces and gripping forces. In particular, there is a demand for a multiple-degree-of-freedom forceps, which allows the operator to feel stronger gripping forces.
As with the manipulators disclosed in Japanese Laid-Open Patent Publication No. 2002-102248 and Japanese Laid-Open Patent Publication No. 2004-301275, a wire and pulley mechanism may be applied to such a multiple-degree-of-freedom forceps, which allows the operator to feel gripping forces.
However, the distal-end working unit of a manipulator is required to be quite small in size, because the distal-end working unit is inserted into abdominal cavities and used within small regions. If the wire and pulley mechanism incorporated in the distal-end working unit of the manipulator is reduced in size in order to reduce the size of the distal-end working unit thereof, then the operating angle of the distal-end working unit possibly may be reduced due to such dimensional limitations.
The wire and pulley mechanism incorporated in the distal-end working unit of the manipulator is expected to experience increased wire loads, owing to a large amount of wire wear and bending, since the pulleys thereof have considerably small diameters and are spaced a small distance from each other.